Body mass index and menopausal disorders during menopause affect vasomotor symptoms of postmenopausal Japanese breast cancer patients treated with anastrozole: a prospective multicenter cohort study of patient-reported outcomes.

Background: Adverse events related to endocrine therapies have a major impact not only on patients' quality of life but also on treatment discontinuation. Although vasomotor symptoms induced by aromatase inhibitors are frequently recognized, risk factors, especially for Japanese women, are not well reported. To identify risk factors for vasomotor symptoms of Japanese breast cancer patients treated with adjuvant anastrozole, we conducted a prospective cohort study based on patient-reported outcomes (PROs).
Patients and Methods: For this prospective cohort study (SAVS-JP, UMIN000002455), 391 postmenopausal Japanese estrogen receptor-positive breast cancer patients who were treated with adjuvant anastrozole were recruited from 28 centers. The PRO assessment was obtained from a self-reported questionnaire at baseline, 3, 6, 9 and 12 months between August 2009 and April 2012. Vasomotor symptoms, comprising hot flashes, night sweats, and cold sweats, were categorized into four grades (none, Grade 1: mild, Grade 2: moderate, Grade 3: severe). Pre-existing symptoms were only included if they had become worse than at baseline.
Results: Hot flashes, night sweats, and cold sweats at baseline were reported by 20.5, 15.1, and 8.2 % of the patients, respectively, and new appearance or worsening of symptoms in comparison with baseline by 38.4, 29.3, and 28.7 %, respectively. About 80 % of newly occurring symptoms were Grade 1, and less than 5 % were Grade 3. Vasomotor symptoms were reported by 201 out of 362 patients (55.5 %) during the first year and the mean time to onset was 5.6 months. Patients with vasomotor symptoms were significantly younger (mean 62.8 years, range 38-86 vs 64.7 years, range 37-84; p = 0.02), had higher body mass index (BMI) (23.4 kg/m ² , range 15.8-39.9 vs 22.4 kg/m ² , range 15.8-34.9; p = 0.01), had vasomotor symptoms sooner after menopause (12.4 years, range 0-51 vs 15.1 years, range 1-37; p = 0.002), and had more menopausal disorders during menopause (63.3 vs 36.7 %; p = 0.002). Multivariate analysis showed that BMI [odds ratio (OR) 1.09 per unit of increase, 95 % confidence interval (CI) 1.02-1.16; p = 0.009] and experiencing menopausal disorders (OR 2.11, 95 % CI 1.35-3.30; p = 0.001) were significantly associated with vasomotor symptoms.
Conclusion: High BMI and experiencing menopausal disorders at menopause were found to be significantly associated with the occurrence of vasomotor symptoms. These findings are expected to prove useful for the management of postmenopausal Japanese women treated with aromatase inhibitors.